Meningeal stem cell signals for improving sensorimotor and cognitive outcomes after stroke Mortality after stroke has decreased. The challenge now is how to deal with the accumulating burden of sensorimotor deficits and post-stroke dementia in surviving patients. In this proposal, we will investigate the meninges as a novel source of stem cell signals that may potentially assist with neurovascular unit recovery. Our pilot data suggest that: (i) meningeal multipotent stem cells (MeSCs) migrate to perivascular space after focal ischemia, (ii) MeSC response may be significant, accounting for up to 30% of CD271 ?total stem cell response?, (iii) this is an ?active process? since inhibiting CXCR4 decreased MeSC migration, (iv) MeSC response may be a relevant therapeutic target since it can be significantly amplified by blocking CD271- mediated stem cell death with LM11A-31, whereas blocking SDF-1 signaling with AMD3100 decreased MeSC migration and worsened blood-brain barrier (BBB) injury; (v) beneficial actions of MeSC may involve restoration of vascular integrity and upregulation of TGF-?-stimulated macrophages that further promote neurogenic responses, and finally (vi) models and methods to dissect this phenomenon are feasible including molecular tools, vasculome mapping, behavioral tests, and in vivo imaging in our collaborating labs. Based on our pilot data, we hypothesize that (a) brain endothelial cells and astrocytes secrete SDF-1 into perivascular space to attract MeSCs, (b) MeSCs restore damaged BBB and rescue the vasculome, (c) MeSC crosstalk with perivascular macrophages promotes TGF-?-mediated neurogenesis, and (d) MeSC-mediated neurovascular unit recovery ameliorates sensorimotor deficits and post-stroke dementia. We have 3 specific aims. In Aim 1, we will map the profile of MeSC proliferation, accumulation, and differentiation in focal cerebral ischemia. In Aim 2, we will investigate cellular mechanisms of crosstalk between MeSCs and vascular/perivascular cells that underlie MeSC migration, BBB repair, vasculome renormalization and neurogenesis. In Aim 3, we will use gain and loss-of-function experiments to modify MeSC-mediated neurovascular remodeling, and assess sensorimotor and cognitive outcomes in vivo. Our experiments will utilize cell cultures and animal models. Molecular tools include a combination of pharmacologic activators/inhibitors, CRISPR/cas9, and cre-lox systems to modify specific pathways and genes. Translational relevance will be assessed with in vivo imaging and long-term outcomes. This project should define a novel mechanism wherein meningeal stem cells communicate with the neurovascular unit, and hopefully provide new approaches to improve sensorimotor recovery and ameliorate post-stroke dementia.